Referring to FIGS. 1A and 1B of the drawings, the reference numeral 100 generally designates a conventional bed scanner. Scanner 100 generally comprises a housing 118 that includes a translucent or transparent sheet 112, which is commonly referred to as “scan glass.” Below the sheet 112, there is a carriage 102, which is mounted on a track 120, that moves between initial and final positions. As the carriage 102 moves between the initial and final positions, the light source 104 transmits light through sheet 102. Light is then reflected off the scanned item along the optical axis 110 (through lens array 106) to image sensor 108 (which is generally a CMOS or charged coupled device (CCD) sensor array).
Turning to FIG. 1C, one line of sensor 108 is shown. This line includes sensors 114-1 to 114-L that are sensitive to red, blue, and green wavelengths of visible spectrum (which are commonly used in color scanners). Each of these sensors 114-1 to 114-L is coupled to one of the drivers 116-1 to 116-L so as to generate output signals OUT1 to OUTL.
Generally, the sensor 108 is divided in to several parts or sections where each part or sections includes several sensors (such as sensor 114-1). Typically, there are M parts or sections that include N sensors. As shown in FIG. 2, each of the M parts of section is associated with one of the input devices 202-1 to 202-M (where each has N channels) of processing circuitry 200. These input devices 202-1 to 202-M are typically N-channel analog front ends or AFEs that generate signals for a processing unit or processor 204. Because each of the input devices 202-1 to 202-M is a separate integrated circuit or IC (where each has some differences due to manufacturing process variations), there is skew between the inputs to the processing unit 204. Thus, there is a need for a method and/or apparatus that compensates for skew.
Some examples of conventional circuits are: U.S. Pat. Nos. 6,696,995; 7,006,021; 7,342,520; U.S. Patent Pre-Grant Publ. No. 2009/0259781.